Brush structures have long been used in a variety of environments including floor maintenance equipment. One type of brush structure is disclosed in U.S. Pat. No. 2,879,534. Such brush structure includes a plurality of plies of wound paper which is impregnated with a moisture-proofing and hardening agent. Tubes of this material have a plurality of tufts or bundles of fibers secured in cavities. This brush structure is perhaps the most commonly used and is relatively inexpensive in manufacture. It is well recognized that such paper-backed brushes have certain disadvantages. For example, paper-backed brushes are relatively dimensionally unstable. The lack of stability is particularly noticeable when the brush structure becomes damp; for example, when encountering surface water during sweeping or scrubbing. The water seeps into the paper and the paper begins to swell. Such paper-backed brushes are also susceptible to damage if the edge portions are struck by any hard objects. This may occur during shipment and handling of such brush structures; also, such damage may occur if the brush is removed from the floor maintenance equipment for any purpose such as repair of the equipment.
One highly stable brush structure includes a solid plastic backing member, for example of polypropylene, which has a plurality of bristle bundles or tufts mounted therein. This structure is strong, stable, and durable. However, it is very heavy and costly from a materials standpoint. Such a brush structure has the advantage that it is not susceptible to swelling due to impregnation by moisture.
An improved lightweight brush structure is shown in U.S. Pat. No. 3,614,801 issued to the Tennant Company. The latter provides a tubular brush including a backing member having a foamed plastic material as a core with an inner and an outer skin of more dense plastic material. This rotary tubular brush structure is lightweight and dimensionally stable. It has a high degree of durability and is not susceptible to damage by water. This rotary brush structure, however, is somewhat complicated in manufacture, which has a significant effect on the cost.